Gear train arrangements

ABSTRACT

Gear train arrangements for transmitting a power from a driving source to a driven member at more than three speeds in one direction and another speed in the opposite direction, the gear train arrangements using basically three planetary gear sets and at least five friction elements such as clutches and brakes which are selectively actuated to selectively engage the rotary members of the three planetary gear sets to deliver an output power at the above said speeds. The gear train arrangements are specifically adapted for use in an automatic transmission system of a motor vehicle using a torque converter or fluid coupling.

United States Patent [191 Mori et a1.

[ Sept.'l7, 1974 1 1 GEAR TRAIN ARRANGEMENTS [75] Inventors: Yoichi Mori, Yokohama; Nobuo Okazaki, Chigasaki; Kunio Ohtsuka; Tetsuya lijima, both of Tokyo, all of Japan [73] Assignee: Nissan Motor Company, Limited,

Yokohama City, Japan [22] Filed: Sept. 13, 1972 [2]] Appl. No.: 288,552

Related U.S. Application Data [62] Division of Ser. No. 30,496, April 21, 1970, Pat. No.

[30] Foreign Application Priority Data July 14, 1969 Japan i. 4465068 [52] U.S. Cl. 74/688, 74/765 [51] Int. Cl. Fl6h 47/08, F16h 57/10 [58] Field of Search; 74/759 688 [56] References Cited UNITED STATES PATENTS 3,282,131 11/1966 Smith 74/759 X 3.398606 8/1968 Utter 74/759 Primary E.\'aminerBenjamin W. Wyche Assistant Examiner-P. S. Lall Attorney, Agent, or Firm-Depaoli & OBrien [57] ABSTRACT Gear train arrangements for transmitting a power from a driving source to a driven member at more than three speeds in one direction and another speed in the opposite direction, the gear train arrangements using basically three planetary gear sets and at least five friction elements such as clutches and brakes which are selectively actuated to selectively engage the rotary members of the three planetary gear sets to deliver an output power at the above said speeds. The gear train arrangements are specifically adapted for use in an automatic transmission system of a motor vehicle using a torque converter or fluid coupling.

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GEAR TRAIN ARRANGEMENTS This is a division of Ser. No. 30,496, filed Apr. 21, 1970, now US. Pat. No. 3,701,293, and is directed to the invention shown in FIG. 17.

This invention relates to gear train arrangements for a transmission system of a motor vehicle and, more particularly, to gear train arrangements of planetary gear type adapted to provide basically four forward and one reverse vehicle speeds.

A usual gear train arrangement using a planetary gear system is made up of a combination of one or more, similar or different, planetary gear sets each having one or more planet pinions and is operated through actuation of friction elements such as clutches and brakes which are arranged to attain a desired combination of gear ratios. Typical of such gear train arrangement is the one that uses three simple planetary gear sets which are combined together to provide three forward and one reverse vehicle speeds. (It may be noted that the term simple planetary gear set as herein used is intended to refer to a planetary gear set having a single planet pinion.)

Foremost of the practical requirements of a gear train arrangement to attain an increased number of vehicle speeds is a wide selection of the combinations of gear ratios, which requirement, however, is reflected by an increased number of component parts of the gear train arrangement and complicated gear shifting operations.

In order that the gear train be snugly accommodated within a limited space in the transmission system, every component of the planetary gear system should be as small in dimensions as possible. From the view point of production economy, moreover, it is desired that the number of the component parts of the gear train be reduced to a minimum and that the parts corresponding in function be fabricated to be common in geometry to one another so as to permit ofquantity production. Another important requirement of the gear train of a transmission system is the ease of gear shifting operations.

It is, therefore, an object of the invention to provide gear train arrangements adapted to provide basically four forward and one reverse vehicle speeds.

Another object is to provide gear train arrangements providing essentially four forward and one reverse vehicle speeds with wide selection of the combinations of gear ratios.

Still another object is to provide gear train arrangements providing four, or even more, forward and one reverse vehicle speeds, which arrangements are constructed with a practically minimum number of component parts and nevertheless can provide practically any desired combination of gear ratios.

Still another object is to provide gear train arrangements that are suited for quantity production.

Still another object is to provide gear train arrangements providing four, or even more, forward and one reverse vehicle speeds with utmost ease of gear shifting operations.

In order to achieve these and other objects, the invention proposes to use various combinations of basically three substantially identically sized planetary gear sets which are operated by means of two or three clutches and two or three brakes. The gear train arrangements using such combinations can be readily modified with incorporation of additional minor arrangements into those providing five or six forward and one reverse vehicle speeds.

In the drawings:

FIGS. 1 to 8 are sectional views schematically showing various preferred embodiments of the invention, each of which embodiments uses three planetary gear sets with two clutches and three brakes to provide four forward and one reverse vehicle speeds;

FIG. 9 is similar to FIGS. 1 to 8 but shows other embodiments using three planetary gear sets with three clutches and two brakes to provide four forward and one reverse vehicle speeds;

FIGS. 10, 11, and 12 are views illustrating still other embodiments using three planetary gear sets with three clutches and three brakes to provide four forward and one reverse vehicle speeds;

FIG. 13 is a view illustrating still another embodiment using four (including one auxiliary) planetary gear sets with three clutches and four brakes to provide four forward and one reverse vehicle speeds;

FIG. 14 is a view illustrating still another embodiment using three planetary gear sets with three clutches and three brakes to provide five forward and one reverse vehicle speeds;

FIG. 15 is a view illustrating still another embodiment using four (including one auxiliary) planetary gear sets with two clutches and three brakes to provide five forward and one reverse vehicle speeds;

FIG. 16 is a view illustrating still another embodiment using four (including one auxiliary) planetary gear sets with three clutches and four brakes to provide six forward and one reverse vehicle speeds;

FIG. 17 is a view illustrating still another embodiment using four planetary gear sets with three clutches and five brakes to provide an overdrive from the fourth speed.

FIGS. la to 16a are diagrams each showing the different revolution speeds of the individual rotary members of the planetary gear sets used in the embodiment illustrated in the correspondingfigure out of FIGS. 1 to 16; and

FIGS. 1b, 4b, 6b, 7b, 8b, 9b and 10b are views each showing a modification of the embodiment illustrated in the corresponding figure without the subscript.

Corresponding reference numerals and characters represent like members in all the figures.

It may be noted in regard to the drawings that only the upper half of each gear train arrangement is herein shown for simplicity of illustration because the gear train arrangement is generally symmetrical with respect to the input and output shafts.

First referring to FIG. 1, the gear train according to one embodiment of the invention is, as customary, connected at one end with an engine through an input shaft 10 and a torque converter orfluid coupling (not shown) and at the other end with a differential (not shown) through an output shaft 11 of the transmission system.

The gear train as shown includes a first, second and third planetary gear sets 12, 13 and 14, all of which are constructed as simple planetary gear sets which are fabricated to be substantially identical in geometry with each other.

The first planetary gear set 12 comprises an outer ring gear R a planet pinion P meshing with the outer ring gear, and a-sun' gear S meshing with uiepian'r pinion. The second planetary gear set 13 similarly comprises an outer ring gear R a planet pinion P meshing with the ring gear, and a sun gear S meshing with the planet pinion. The third planetary gear set 14 also similarly comprises an outer ring gear R a planet pinion P meshing with the ring gear, and a sun gear 8:, meshing with the planet pinion. The planet pinions P P and P are carried on and revolved by pinion carriers l5, l6 and 17, respectively. The ring gears, pinion carriers and sun gears are all rotatable about a common axis which is in line with the axes of the pinion carriers. More detailed discussion on the constructions and motions of the planetary gear set per se is herein omitted because they are well known in the art.

The ring gear R of the first planetary gear set 12 is constantly connected to and rotatable with the planet pinion P of the second planetary gear set 13 through the pinion carrier which forms part of a drum 18. The sun gears S and S of the first and second planetary gear sets 12 and 13, respectively, are constantly connected to and rotatable with the input shaft of the transmission through mechanical linkages 19 and 20, respectively. The ring gear R is constantly connected to and rotatable with the sun gear 8;, of the third planetary gear set 14 through a drum 2]. The pinion carrier 17 is constantly connected to and rotatable with the output shaft 11 of the transmission to carry an output power to the differential (not shown).

The pinion carrier of the planet pinion P, is connected to a first band brake B, which, when applied, holds the planet pinion P stationary. The drum 18 interconnecting the ring gear R, and planet pinion P coacts with a second band brake B which, when applied, holds both the ring gear R and planet pinion P stationary. The drum 21 interconnecting the ring gear R and sun gear 5;, coacts with a third band brake 8,, which, when applied, holds both the ring gear R and sun gear 8;, stationary.

Two clutches C and C are provided to selectively connect the ring gear R to the drum 21 and the input shaft 10, respectively.

Now, it is well known in the art that, assuming the revolution speeds of a ring gear, sun gear and pinion carrier ofa given planetary gear set are Nr, Ns and Np, respectively, and the ratio of the number of teeth of the sun gear to the number of teeth of the ring gear is a, then the following equation holds:

(a l)'Np Nr a-Ns.

Thus, for the planetary gear sets 12, I3 and 14, the following equations can be derived:

(a l )'Np Nr oz -,'Ns where the subscripts l, 2 and 3 represent the first, second and third planetary gear sets 12, 13 and 14, respectively.

In consideration of the constant connections between some of the rotary members of the planetary gear sets, the following equations hold:

Ns, Ns Nr, N12 and Nr Ns The speeds Ns, and Np are equal to the revolution speeds of the input and output shafts l0 and 11, respectively.

These mathematical relations between the revolution speeds of the individual rotary members of the planetary gear sets can be graphically illustrated in FIG. 1a, wherein points L, M and N are given on a line 0-0 in such a manner that the following relations are maintained:

OL/LM a ON/NO a and O'L/LO 01 Thus, the points 0, L, M, N and 0' stand for the relations between those individual rotary members of the planetary gear sets which are respectively shown below these points. The speed vector of each rotary member of the planetary gear sets is indicated by a length from the respective point 0, L, M, N or O on a line extending therefrom.

When in operation, the first speed is to be selected, the second clutch C is coupled and the first brake B, applied. The ring gear R of the third planetary gear set 14 now rotates with the input shaft 10 and the planet carrier 15 is held stationary, so that the following equations hold:

Ns Nr and Np, 0.

In this condition, the sun gear 8, is rotated directly by the input shaft 10 with the planet pinion P held stationary so that the ring gear R and the pinion carrier 16 of the planet pinion P rotate at a speed corresponding to a vector NN, in FIG. 1a. With the sun gear S rotating with the input shaft 10, the ring gear R and the sun gear 8;; rotate at a speed corresponding to a vector 00,. The ring gear R rotating with the input shaft and the sun gear 8;, rotating at a speed corresponding to 0'0, the pinion carrier 17 of the planet pinion P rotates at speed corresponding to AA providing a gear ratio for the first forward vehicle speed.

The gear ratio establishing the first speed thus delivered from the output shaft 11 is thus expressed as:

When the vehicle speed is to be shifted from the first to the second speed, then the first brake B, is released and instead the second brake B is applied with the second clutch C kept coupled. Thus:

Nr, N112 0.

With the brake B applied, the planet pinion P is held stationary and the sun gear 5;, rotates with the input shaft 10 so that the ring gear R and the sun gear 5;, are rotated at a speed corresponding to a vector 0'0 in FIG. la. With the clutch C coupled, the ring gear S rotates with the input shaft 10 so that the pinion carrier 17 of the planet pinion P rotates at a speed corresponding to a vector AA providing a gear ratio for the second forward speed.

The gear ratio for the second vehicle speed is thus expressed as:

When the speed is to be shifted from the second to the third speed, the second brake B is released and instead the third brake 8;, applied with the second clutch C kept coupled. Thus:

Nl'g N53 0 and Nrg N32.

With the brake 8;, applied and the clutch C coupled, the sun gear S is held stationary and the ring gear R rotates with the input shaft 10 so that the pinion carrier 17 of the planet pinion P rotates at a speed corresponding to a vector AA, which provides a gear ratio to establish the third forward speed.

The gear ratio for the third speed is thus expressed as:

In order to streamline the shifting between the first and second speeds, a one-way clutch 23 may be provided on the planet carrier of the first planetary gear set 12, as illustrated in FIG. 1b, if desired.

5 Nsl/NQ: 1 It will be appreciated that the gear train shown in When the speed is to be shifted from the third to the FIGS. 1 and 1b are suited to provide ease of gear shiftfourth speed, then the third brake B is released and the ing operations because the gear ratios can be changed first clutch C, coupled with the second clutch C kept merely by releasing only one of the clutches and brakes coupled. Thus: 10 and actuating another one of them.

FIG. 2 illustrates another form of the gear train ac- Nrz cording to the invention. The gear train is constructed With the brakes B,, B and B released and the essentially similarly to the gear train of FIG. 1 so as to clutches C, and C coupled, all the planetary gear sets provide four forward and one reverse speeds with use rotate with the input shaft so that the revolution speed 5 of three identical planetary gear sets 12, 13 and 14 of the pinion carrier 17 of the planet pinion P is equal which are operated by two clutches C, and C and three to the speed of the input shaft, as indicated by a vector band brakes B,, B and B AA, in FIG. la.

The gear ratio for the fourth speed attained in this The first clutch C, is linked on the one hand with the manner is thus expressed as: input shaft 10 of the transmission and on the other with NS N l the ring gear R, of the first planetary gear set 12. The p3 second clutch C which is also linked with the input When the vehicle is to be moved backwardly, the first shaft 10, is linked with both the sun gears S, and S of clutch C, is coupled and the second brake B applied. the first and second planetary gear sets 12 and 13, re- Thus: Nr Nr and Nr, Np O. spectively, through a drum 24 for the first band brake With the brake B applied and the sun gear S rotat- B,. The sun gears S, and S, are as a result constantly ing with the input shaft 10, the ring gear R and the sun connected together and rotatable with each other. The gear 5; rotate at a speed corresponding to a vector planet pinion P, of the first planetary gear set 12 is con- O'O Since, in this instance, the clutch C, is coupled, stantly connected to and rotatable with the ring gear R, the ring gear R also rotates at a speed equal to the of the second planetarys gear set 13, sun gear 8,, of the speed of the ring gear R and sun gear 8,. Both the ring third planetary gear set 14, and output shaft 11 of the gear R and sun gear 8, rotating at the speed corretransmission through the pinion carrier 15 and an intersponding to 0'0 the planetary gear set 14 rotates in mediate shaft 25. The planet pinion P of the second its entirety at this speed. The output shaft 11 is thus roplanetary gear set 13 is constantly connected to and rotated at a speed corresponding to 0'0 in a direction tatable with the planet pinion P of the third planetary opposite to the rotation of the input shaft 10. gear set 14 through the pinion carriers 16 and 17 which The gear ratio for the reverse speed thus established form part of a drum 26 for the second band brake B is thus expressed as:' The ring gear R of the third planetary gear set 14 is connected to a drum 27 for the third band brake B Nsl/Npa 1M2) The conditions of the clutches and the brakes for the The conditions of the clutches and brakes for the difdifferent vehicle speeds and the gear ratios attained in ferent vehicle speeds and the gear ratios attained under these conditions are tabulated in Table II; the gear rathese conditions are tabulated in Table I, wherein the tics are calculated in a manner similar to that discussed sign refers to that the related clutch or brake is acin connection with the gear train of FIG. 1.

Table II C, C B, B, B, Gear Ratios Forward lst l+a,+a,/ol 2nd l'l'm/ a 2 a)/ z( z) L82) 3rd l+a, L45) 4th I L Rev. l/a, (-2.22)

tuated and the sign refers to that the clutch or brake is kept released. The gear ratios indicated in the parentheses are derived on the assumption that a, a,

When the first forward speed is selected, the clutch C, is coupled and the brake B applied. In this instance, the operations of the individual rotary members will be a 0.45. (This will apply to all the tables which are easily understood if it is assumed that the output shaft hereinafter presented.)

11 is first rotated to impart a rotational effort to the input shaft 10, conversely to the actual operation. Thus, if the output shaft 11 is rotated at a speed corresponding to a vector AA, in FIG. 2a, then the ring gear R and the pinion carrier 15 of the planet pinion P, will It will now be appreciated that the gear train of FIG. 2 is, similarly to that of FIG. 1, adapted to provide ease of gear shifting operations because the gear ratios can be changed merely by releasing only one of the rotate at the same speed as the output shaft 11. With clutches and brakes and actuating another one of them the brake B applied, the planet pinion P is held staandthat, the f p power can P dierived m tion-my so that the Sun gears 5 d S rotate at a speed the intermediate section of the gear train without sacricorresponding to a vector O'O,. Such rotation of the f' the oulplft torque f s can utlhzed sun gear 51 and the revolution of the planet pinion p m a front-engine front-driving or rear-engine rear- (which revolves at a speed equal to the revolution drlven Q Vehlcle- Speed f the output h ft 11) will dictate the Speed at FIG. 3 illustrates Still another form of the gear train which the ring gear R1 f the first planetary gear set 12 according to the invention constructed to provide four rotates as represented by a vector Q02 in FIG 2a The forward and one reverse speeds. The gear tram also has driving force is actually carried to the input shaft 10, three identical Planetary gear Sets 13 and 14 with not to the output shaft 11, so that the flow of rotation 15 {W0 Clutches l and 2 and three brakes B! 2 and 3, is exactly inverse from that discussed above. Thus, it is as Shownapparent that the first speed corresponds with the vec- The first clutch C1 is on one side With the input tor AA, in FIG. 2a. shaft 10 and on the other with the ring gear R, of the When the speed is shifted from the first to the second first planetary gear set 12 through a drum 28 of the first speed, then the brake B is released and the brake B band brake B,. The second clutch C is linked on one is applied with the clutch C, kept coupled. Here, it is side with the input shaft 10 and on the other with the also assumed that the driving force is initially transsun gears 5,, S and S of the first, second and third ferred to the. output shaft 11. If the output shaft 11 is planetary gear sets l2, l3 and 14, respectively, through rotated at a speed corresponding to a vector AA, in an intermediate shaft 29. The sun gears 5,, S and S, are FIG. 2a, the sun gear 5,, rotates with the output shaft thus constantly connected to each other and rotatable 11. The ring gear R being held stationary with the with the input shaft 10 when the clutch C is coupled. brake 8;, applied, the pinion carriers 17 and 16 rotate The pinion carrier 15 of the planet pinion P, of the first at a speed corresponding to a vector MM. Since, in planetary gear set 12 is constantly connected to and rothis instance, the ring gear R rotates with the output tatable with the ring gear R of the second planetary shaft 11 at a speed corresponding to the vector AA gear set 13 through a drum 30 for the second band the sun gears S and S, rotate at a speed corresponding brake B The pinion carrier 16 of the planet pinion P to the vector OO,. The planet pinion P, is rotated with of the second planetary gear set 13 is constantly conthe pinion carrier 15 rotating with the output shaft 11 nected to and rotatable with the ring gear R of the so that the ring gear R, will rotate at a speed correthird planetary gear set 14 and is linked with the third sponding to the vector 00; in FIG. 2a. The actual operbrake 8,, through a drum 31. The pinion carrier 17 of ations of the planetary gear sets are exactly converse the planet pinion P of the third planetary gear set 14 from those discussed above but, anyway, it is apparent is connected to the output shaft 11. A one-way brake that the second speed corresponds to the vector AA, in 32 is provided to prevent the planet pinion P and sun FIG. 2a. gear 5,, from rotating in a direction opposite to the rota- When the speed is shifted from the second to the tion of the input shaft 10. third speed, the brake B, in lieu of the brake B is now In consideration ofthe constant connections between applied with the clutch C, kept coupled, so that the sun some of the rotary members of the planetary gear sets gears S, and S, are held stationary and the ring gear R, in this embodiment, the following relations hold: rotates with the input shaft 10. The pinion carrier 15 supporting the planet pinion P,, therefore, rotates at a NPZ NPI and N51: N82 NSW speeds corresponding to a vector AA, providing a gear ratio for the third forward speed. The conditions of the clutches and brakes for the dif- When the speed is further shifted up from the third ferent vehicle speeds and the gear ratios attained in to the fourth speeds, all the brakes are applied and the these conditions are tabulated in Table III.

Table III C, C, B, B, B, Gear Ratios Forward lst a,,+l/a (3.22) 2nd a +a u +a l /a +a,'a -,+a l .90) 3rd (a,+l )(a,+l )(a;,+l )/a,+(a,+l )(a,+a,-a,,+a (1.49) 4th 1 (1.00 Rev. :i+ i+ r' 2 zl/ a clutches are coupled so that the first planetary gear set Now, for the first forward speed, the clutch C is cou- 12 rotates in its entirety at the same speed as the input pled with the brakes B,, B and 8;, all released. The shaft 10. The speed of the input shaft 10 is in this manthree planetary gear sets rotate together at the same ner transferred to the output shaft 11 as it is. speed as the input shaft 10. In this instance, the ring For effecting the reverse movement of the vehicle, gear R tends to rotate in a direction opposite to the dithe clutch C -is coupled and the brake B, applied. The sun gear 8, now rotates with the input shaft 10 with the planet pinion P held stationary so that the ring gear R rotates at a speed corresponding to a vector LL, which provides a gear ratio to establish the reverse speed.

rection of rotation of the planetary gear sets because of the running resistance of the vehicle as transferred thereto from the wheel axles. Such tendency is, however, obstructed by the one-way brake 32 so that the relation Nra 0 holds. The output speed thus delivered 

1. A gear train for transmitting rotary drive from a rotary drive source to a driven member, said change speed gear train comprising:
 1. an input shaft connected to said source to be rotated thereby in one given direction only;
 2. an output shaft connected to said driven member;
 3. a first planetary gear set;
 4. a second planetary gear set;
 5. a third planetary gear set and each of said planetary gear sets comprising: a. firstly, a rotary member in the form of an outer ring gear which is internally toothed; b. secondly, a rotary member in the form of a sun gear which is externally toothed; c. thirdly, a planet pinion meshing both with said ring gear and with said sun gear; and d. fourthly a rotary member in the form of a pinion carrier rotatably carrying the planet pinion;
 6. said input shaft, said output shaft and said rotary members of said first, second and third planetary gear sets all being rotatably about a common axis;
 7. said change speed gear train also comprising a plurality of mechanical linkages each constantly connecting together a respective pair of said rotary members to prevent rotation other than synchronous rotation of the respective pair of rotary members;
 8. a first clutch and a second clutch each selectively operable to connect said input shaft to at least one respective one of said rotary members;
 9. a first brake, a second brake and a third brake each selectively operable to brake at least one respective one of said rotary members against rotation about said axis;
 10. said change speed gear train being adapted to produce, upon rotation of said input shaft in said given direction, rotation of said output shaft selectively in said given direction with at least four different speeds and also selectively in the opposite direction with one speed and further comprising a fourth planetary gear set comprising: a. firstly, a rotary member in the form of a sun gear which is externally toothed; and b. secondly, a planet pinion which meshes with the lastmentioned sun gear;
 2. said second input shaft being connected constantly to the planet carrier of said second planetary gear set and operatively connected to another driving source through said third clutch;
 2. A gear train as claimed in claim 1, wherein said second brake is combined with a one-way brake preventing the pinion carrier of said first planetary gear set and the ring gear of said second planetary gear set from rotating in the direction opposite to said given direction of said input shaft.
 2. an output shaft connected to said driven member;
 3. a first planetary gear set;
 3. said first brake being operable and said third clutch being couplable for selecting an overdriving speed from said fourth speed in said given direction, whereby rotational drive can be transmitted from either of said driving sources to said output shaft at five different speeds in said given direction and the one speed in the opposite direction.
 3. A gear train as claimed in claim 2, wherein said third second brake is combined with a one-way brake preventing the pinion carrier of said second planetary gear set and the ring gear of said third planetary gear set from rotating in the direction opposite to said given direction of said input shaft.
 4. A gear train as claimed in claim 3 and further comprising:
 4. a second planetary gear set;
 5. a third planetary gear set and each of said planetary gear sets comprising: a. firstly, a rotary member in the form of an outer ring gear which is internally toothed; b. secondly, a rotary member in the form of a sun gear which is externally toothed; c. thirdly, a planet pinion meshing both with said ring gear and with said sun gear; and d. fourthly a rotary member in the form of a pinion carrier rotatably carrying the planet pinion;
 6. said input shaft, said output shaft and said rotary members of said first, second and third planetary gear sets all being rotatably about a common axis;
 7. said change speed gear train also comprising a plurality of mechanical linkages each constantly connecting together a respective pair of said rotary members to prevent rotation other than synchronous rotation of the respective pair of rotary members;
 8. a first clutch and a second clutch each selectively operable to connect said input shaft to at least one respective one of said rotary members;
 9. a first brake, a second brake and a third brake each selectively operable to brake at least one respective one of said rotary members against rotation about said axis;
 10. said change speed gear train being adapted to produce, upon rotation of said input shaft in said given direction, rotation of said output shaft selectively in said given direction with at least four different speeds and also selectively in the opposite direction with one speed and further comprising a fourth planetary gear set comprising: a. firstly, a rotary member in the form of a sun gear which is externally toothed; and b. secondly, a planet pinion which meshes with the last-mentioned sun gear;
 11. The planet pinion of said fourth planetary gear set being rotatably carried by the planet carrier of said second planetary gear set, wherein the sun gears of said first and second planetary gear sets are connected constantly to each other, th sun gears of said third and fourth planetary gear sets are connected constantly to each other, the pinion carrier of said first planetary gear set is connected constantly to the ring gear of said second planetary gear set, the pinion carrier of said second planetary gear set is connected constantly to the ring gear of said third planetary gear set, and the planet carrier of said third planetary gear set is connected constantly to said output shaft;
 11. The planet pinion of said fourth planetary gear set being rotatably carried by the planet carrier of said second planetary gear set, wherein the sun gears of said first and second planetary gear sets are connected constantly to each other, th sun gears of said third and fourth planetary gear sets are connected constantly to each other, the pinion carrier of said first planetary gear set is connected constantly to the ring gear of said second planetary gear set, the pinion carrier of said second planetary gear set is connected constantly to the ring gear of said third planetary gear set, and the planet carrier of said third planetary gear set is connected constantly to said output shaft;
 12. said first clutch being operatively connected between said input shaft and the ring gear of said said first planetary gear set and couplable for selecting the fourth speed in said given direction and the one speed in the opposite dIrection;
 13. said second clutch being operatively connected between said input shaft and the sun gears of said first and second planetary gear sets and couplable for selecting the first, second, third and fourth speeds in said given direction;
 14. said first brake being operatively connected to the ring gear of said first planetary gear set and operable for selecting the third speed in said given direction;
 15. said third brake being operatively connected to the pinion carrier of said second planetary gear set and the ring gear of said third planetary gear set and operable for selecting the second speed in said given direction; and
 16. said second brake being operatively connected to the planet carrier of said first planetary gear set and the ring gear of said second planetary gear set and operable for selecting the one speed in said opposite direction.
 12. said first clutch being operatively connected between said input shaft and the ring gear of said said first planetary gear set and couplable for selecting the fourth speed in said given direction and the one speed in the opposite dIrection;
 13. said second clutch being operatively connected between said input shaft and the sun gears of said first and second planetary gear sets and couplable for selecting the first, second, third and fourth speeds in said given direction;
 14. said first brake being operatively connected to the ring gear of said first planetary gear set and operable for selecting the third speed in said given direction;
 15. said third brake being operatively connected to the pinion carrier of said second planetary gear set and the ring gear of said third planetary gear set and operable for selecting the second speed in said given direction; and
 16. said second brake being operatively connected to the planet carrier of said first planetary gear set and the ring gear of said second planetary gear set and operable for selecting the one speed in said opposite direction. 